3 * Point multiplication for elliptic curves
5 * (c) 2004 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
33 /*----- Main code ---------------------------------------------------------*/
35 /* --- @ec_imul@, @ec_mul@ --- *
37 * Arguments: @ec_curve *c@ = pointer to an elliptic curve
38 * @ec *d@ = pointer to the destination point
39 * @const ec *p@ = pointer to the generator point
40 * @mp *n@ = integer multiplier
42 * Returns: The destination @d@.
44 * Use: Multiplies a point by a scalar, returning %$n p$%. The
45 * @imul@ variant uses internal representations for argument
49 ec
*ec_imul(ec_curve
*c
, ec
*d
, const ec
*p
, mp
*n
)
54 if (t
.x
&& (n
->f
& MP_BURN
))
63 if (MP_LEN(n
) < EXP_THRESH
)
72 ec
*ec_mul(ec_curve
*c
, ec
*d
, const ec
*p
, mp
*n
)
76 return (EC_OUT(c
, d
, d
));
79 /* --- @ec_mmul@, @ec_immul@ --- *
81 * Arguments: @ec_curve *c@ = pointer to an elliptic curve
82 * @ec *d@ = pointer to the destination point
83 * @const ec_mulfactor *f@ = pointer to vector of factors
84 * @size_t n@ = number of factors
86 * Returns: The destination @d@.
88 * Use: Does simultaneous point multiplication. The @immul@ variant
89 * uses internal representations for arguments and result.
95 static ec
*immul(ec_curve
*c
, ec
*d
, ec_mulfactor
*f
, size_t n
)
99 for (i
= 0; i
< n
; i
++) {
101 if (MP_NEGP(f
[i
].exp
))
102 EC_NEG(c
, &f
[i
].base
, &f
[i
].base
);
103 if (f
[i
].base
.x
&& f
[i
].exp
->f
& MP_BURN
)
104 f
[i
].base
.x
->f
|= MP_BURN
;
108 for (i
= 0; i
< n
; i
++)
109 EC_DESTROY(&f
[i
].base
);
114 ec
*ec_immul(ec_curve
*c
, ec
*d
, const ec_mulfactor
*f
, size_t n
)
116 ec_mulfactor
*ff
= xmalloc(n
* sizeof(ec_mulfactor
));
119 for (i
= 0; i
< n
; i
++) {
120 EC_CREATE(&ff
[i
].base
);
121 EC_COPY(&ff
[i
].base
, &f
[i
].base
);
122 ff
[i
].exp
= f
[i
].exp
;
124 return (immul(c
, d
, ff
, n
));
127 ec
*ec_mmul(ec_curve
*c
, ec
*d
, const ec_mulfactor
*f
, size_t n
)
129 ec_mulfactor
*ff
= xmalloc(n
* sizeof(ec_mulfactor
));
132 for (i
= 0; i
< n
; i
++) {
133 EC_CREATE(&ff
[i
].base
);
134 EC_IN(c
, &ff
[i
].base
, &f
[i
].base
);
135 ff
[i
].exp
= f
[i
].exp
;
138 return (EC_OUT(c
, d
, d
));
141 /*----- That's all, folks -------------------------------------------------*/